In golf balls commercially selling, there are solid golf balls such as two-piece golf ball, three-piece golf ball and the like, and thread wound golf balls. Recently, the solid golf balls, of which flight distance can be improved while maintaining soft and good shot feel at the time of hitting as good as the conventional thread wound golf ball, generally occupy the greater part of the golf ball market. Multi-piece golf balls represented by three-piece golf ball have good shot feel while maintaining excellent flight performance, because they can vary hardness distribution, when compared with the two-piece golf ball (Japanese Patent Kokai Publication Nos. 24085/1995, 239068/1997, 271249/2000, 107327/2000, 317015/2000 and the like).
In Japanese Patent Kokai Publication No. 24085/1995, a three-piece solid golf ball comprising a center core, an intermediate layer and a cover is disclosed. The center core has a diameter of at least 29 mm and specific gravity of less than 1.4, the intermediate layer has a thickness of at least 1 mm, specific gravity of less than 1.2 and JIS-C hardness of at least 85, the cover has a thickness of 1 to 3 mm, and the specific gravity of the intermediate layer is lower than that of the center core.
In Japanese Patent Kokai Publication No. 239068/1997, a three-piece solid golf ball comprising a core, an intermediate layer and a cover is disclosed. The core has a center hardness in JIS-C hardness of not more than 75 and a surface hardness in JIS-C hardness of not more than 85, the surface hardness is higher than the center hardness by 8 to 20, the hardness in JIS-C hardness of the intermediate layer is higher than the surface hardness of the core by not less than 5, the hardness in JIS-C hardness of the cover is lower than that of the intermediate layer by not less than 5, and the dimples occupy at least 62% of the ball surface. In the two golf balls, the hardness of the intermediate layer is higher than that of the cover, but the rigidity of the intermediate layer is increased together with the hardness, and thus shot feel is poor.
In Japanese Patent Kokai Publication No. 271249/2000, a multi-piece solid golf ball comprising a core consisting of an inner core and an outer core formed on the inner core, and one or more layers of cover covering the core is disclosed. The inner core has a diameter of 30 to 39.5 mm and a center hardness in JIS-C hardness of 55 to 70, and is formed from press molded rubber composition comprising polybutadiene, a co-crosslinking agent, an organic peroxide and a filler, and the JIS-C hardness at a distance of 15 mm from the center point of the inner core is higher than the center hardness by 5 to 20; the outer core has a thickness of 0.3 to 2.0 mm and a surface hardness in JIS-C hardness of 75 to 90, and is formed from press molded rubber composition comprising polybutadiene, a co-crosslinking agent, an organic peroxide and a filler, and the surface hardness of the outer core is higher than the center hardness of the inner core by 10 to 35; and the cover contains thermoplastic resin as a base resin, and the outmost cover layer has a thickness of 1.5 to 2.5 mm and a surface hardness in Shore D hardness of 64 to 72. In the golf ball, since the cover hardness is high, the shot feel is poor.
In Japanese Patent Kokai Publication No. 107327/2000, a three-piece solid golf ball comprising a core composed of a center having a diameter 27 to 37 mm and an intermediate layer covering the center, and a cover covering the core is disclosed. The specific gravity of the center (a) is smaller than that of the intermediate layer (b), a surface hardness in JIS-C hardness of the center (Y) is higher than a central point hardness in JIS-C hardness of the center (X) by not less than 8, a surface hardness of the core (Z) is not less than 80, a difference (p−q) between a deformation amount of the center (p) and that of the core (q), when applying from an initial load of 98 N to a final load of 1275 N, is not less than 5, and Shore D hardness of the cover is not more than 60. In the golf ball, since the thickness of the intermediate layer having relatively high hardness is large, the shot feel is poor performance and better durability.
In Japanese Patent Kokai Publication No. 317015/2000, a multi-piece solid golf ball comprising a core consisting of a center and an intermediate layer formed on the center, and a cover covering the core is disclosed. The intermediate layer                (a) is formed from a rubber composition comprising a base rubber, a co-crosslinking agent, an organic peroxide and a filler,        (b) has a hardness in JIS-C hardness of 75 to 90, and the hardness of the intermediate layer is higher than a surface hardness in JIS-C hardness of the center by 1 to 12,        (c) has a thickness of 0.2 to 1.3 mm, and        (d) has a specific gravity of 1.20 to 1.60. In the golf ball, since it is required to use a large amount if the filler in order to increase the specific gravity of the intermediate layer, the rebound characteristics are degraded.        
In the conventional solid golf balls, there has been no golf ball having excellent flight performance while maintaining good shot feel. Therefore, it is required to provide a golf ball having better shot feel and better flight performance.